In a distributed computing environment, jobs are typically spread out across all available servers to provide faster processing and throughput. That is, the workload is distributed to more than one server so that jobs can be processed in parallel, rather than stacking up in the queue of a single machine performing other tasks. In some implementations, the distributed servers may even span different networks and geographical locations.
One example of a load distributing system is disclosed in U.S. Pat. No. 6,070,191. This patent is directed to a server system for processing client requests received over a communication network. The server system includes a cluster of document servers and at least one redirection server. The redirection server receives a client request from the network and redirects it to one of the document servers based upon a set of pre-computed redirection probabilities. Each of the document servers may be an HTTP server that manages a set of documents locally and can service client requests only for the locally-available documents. Documents are distributed across the document servers using a load distribution algorithm. The algorithm uses access rates of the documents as a metric for distributing the documents across the servers and determining the redirection probabilities. The load distribution algorithm attempts to equalize the sum of the access rates of all the documents stored at a given document server across all of the document servers.
Network service providers require high levels of connectivity. Yet, there are many types of failures that can cause connectivity disruptions between one service provider and another. Moreover, network administrators often block certain types of traffic for security or other reasons. Such conductivity failures may negatively impact the performance of typical load balancing systems.